In a bahuvrīhi samāsa the acute accent (udātta) is on the final when the second member is mukha 'mouth' i.e. the actual bodily part of an animal and not used metaphorically.,
Thus गौरमुखः꣡, भद्रमुखः꣡ ॥ Why do we say 'an actual part of a body'? Observe दीर्घमुखा शाला ॥ Here मुख means \entrance or door\. The word स्वाङ्ग means \a non liquid substance actually to be found in living beings &c\. as explained in 3.4.54.,